Collapsible ramps provide a dual benefit. First, they provide a means of bridging the gap between a horizontal raised surface and the ground so that an object or vehicle can be moved along said ramp and be loaded on to the raised surface. Second, they can be folded or slideably compacted into themselves so as to allow for easy storage. The prior art includes several collapsible ramps that fixedly attach to a raised surface, most commonly the tailgate of a truck.
Examples of prior art collapsible loading ramps are shown in Floe U.S. Pat. No. 5,538,308, Curtis U.S. Pat. No. 3,713,553 and Adaway U.S. Pat. No. 4,864,673.
Floe discloses a portable ramp structure constructed by a plurality of pairs of support members having longitudinal channels for mounting a predetermined number of cross members therebetween. Retention chains with associated hooks removably attach the ramp structure to a transport vehicle.
Curtis teaches a loading ramp that secures to a vertically swingable truck tail gate by mounting brackets. The ramp includes two sections hinged together to allow the ramp to fold so it can be stored in a compact form against the tailgate.
Adaway discloses a collapsible ramp comprising an attachment frame, a foldable support structure mounted to the attachment frame by pivotable hinges and a telescoping deck structure of interconnected, essentially rectangular plates. The foldable support structure has longitudinal support members with foldable joints intermediate along the lengths of the members, and these members are pivotally connected to the hinge. The support members fold back on themselves to reduce the ramp to a collapsed state for storage purposes.